Tail seals

Abstract

Tail seal compound (tail seal) for tunnelling machine comprising blown oils, more than 30% by weight of a mineral charge and fibrous material.

The invention claimed is: 
     
       1. A composition useful for preparing tail seals comprising: 
       from about 30 to about 70% by weight of blown oils having Brookfield® viscosity RVT at 25° C., 20 rpm, higher than about 4,000 mPa·s, 
       from about 30 to about 70% by weight of a mineral charge, and 
       from about 2 to about 10% by weight of fibrous material;
 wherein the mineral charge is a non fibrous mineral charge in the form of powder; and 
 the powder has a mean particle size of from about 40 to about 300 microns; 
 
       and wherein the composition is prepared in the substantial absence of talc. 
     
     
       2. The composition of  claim 1  wherein the mineral charge is from about 45 to about 70% by weight of the composition. 
     
     
       3. The composition of  claim 1  wherein the blown oils have Brookfield® viscosity RVT at 25° C., 20 rpm, higher than about 6,000 mPa·s. 
     
     
       4. The composition of  claim 3  wherein the blown oils have Brookfield® viscosity RVT at 25° C., 20 rpm, of at least about 8,000 mPa·s. 
     
     
       5. The composition of  claim 1  wherein the blown oils have an acid number of less than or equal to about 110 mg KOH/g. 
     
     
       6. The composition of  claim 1  wherein the blown oils are produced using an oil selected from the group consisting of: rape seed oil, castor oil, linseed oil, olive oil, soybean oil, palm oil, tall oil, fish oil, menhaden oil, herring oil, sardine oil, cod oil, liver oil, used oils and fats, and mixtures thereof. 
     
     
       7. The composition of  claim 6  wherein the blown oils are produced using castor oil. 
     
     
       8. The composition of  claim 6  wherein the blown oils are produced using used oil. 
     
     
       9. The composition of  claim 5  comprising from about 40 to about 50% by weight of blown oils. 
     
     
       10. The composition of  claim 6  wherein the blown oils are produced at elevated temperatures of from about 60 to about 250° C. by blowing air through the oil. 
     
     
       11. The composition of  claim 6  wherein the blown oils are produced by crosslinking the oil through formation of peroxide bridges and C-C linkages. 
     
     
       12. The composition of  claim 6  wherein the mineral charge is selected from the group consisting of calcium carbonate, hydrated calcium sulphate, barium sulphate and mixtures thereof. 
     
     
       13. The composition of  claim 12  wherein the mineral charge is calcium carbonate. 
     
     
       14. The composition of  claim 1  wherein the fibrous material consists of cellulose fibers. 
     
     
       15. The composition of  claim 14  wherein the cellulose fibers have a length of from about 1 mm to about 5 mm. 
     
     
       16. A method of excavating or tunneling comprising using a tail sealing compound to prevent the penetration of the tunnel or excavation wall by ground water wherein the tail sealing compound comprises: 
       from about 30 to about 70% by weight of blown oils having Brookfield® viscosity RVT at 25° C., 20 rpm, higher than about 4,000 mPa·s, 
       from about 30 to about 70% by weight of a mineral charge, and 
       from about 2 to about 10% by weight of fibrous material; and 
       wherein the tail sealing compound is prepared in the substantial absence of talc. 
     
     
       17. A composition useful for preparing tail seals comprising: 
       from about 30 to about 70% by weight of blown oils having Brookfield® viscosity RVT at 25° C., 20 rpm, higher than about 4,000 mPa·s, 
       from about 30 to about 70% by weight of a mineral charge, and 
       from about 2 to about 10% by weight of fibrous material; 
       wherein the composition is prepared in the substantial absence of talc, pour point depressants and emulsifying agents.